Semiconductor microfabrication employs a lithography process using a resist composition. In lithography, theoretically, the shorter the exposure wavelength becomes, the higher the resolution can be made, as expressed by Rayleigh's diffraction limit formula. The wavelength of an exposure light source for lithography used in the manufacture of semiconductor devices has been shortened year by year as g line having a wavelength of 436 nm, i line having a wavelength of 365 nm and KrF excimer laser having a wavelength of 248 nm. ArF excimer laser having a wavelength of 193 nm seems to be promising as the next-generation exposure light source.
As lenses used for ArF excimer laser steppers have shorter lives than those used for conventional laser steppers having longer wavelength, it is desirable that exposure time to ArF excimer laser light becomes as short as possible. As it is necessary to enhance the sensitivity of resists for the purpose above, chemically amplified resists utilizing the catalytic action of an acid generated by exposure and containing a resin having a group being dissociated by the acid.
It is known that a resin used in the resist for exposure to ArF excimer laser light is better not to have aromatic ring(s) to secure transmittance of the resist and better to have aliphatic ring(s) in place of aromatic ring(s) to provide dry etching resistance. As such a resin, various resins are known (for example, see D. C. Hofer, Journal of Photopolymer Science and Technology, Vol. 9, No. 3, 387-398 (1996)). However, conventionally known resins have been associated with a problem that line edge roughness is deteriorated.